Review of very high-content reclaimed asphalt use in plant-produced pavements: state of the art

TLDR

In the United States, asphalt is the most recycled material with a 99 % reuse rate, yet only 10–20 % of reclaimed asphalt pavement (RAP) is incorporated into mix designs due to degradation and suboptimal practices, although improved management, modern production technologies, and advanced mix‑design knowledge can substantially raise RAP content. This paper reviews state‑of‑the‑art strategies for raising RAP inclusion in asphalt mixtures beyond 40 %, covering best practices for RAP management and the associated economic advantages. It identifies production challenges and typical distresses of high‑RAP mixtures and outlines methods to optimise mix design and production technology to enable sustainable manufacturing.

Abstract

Asphalt is the most recycled material in the USA at a re-use rate of 99%. However, by average only 10–20% reclaimed asphalt pavement (RAP) is used in a given mix design and large part of the RAP is degraded for use in lower value applications. The amount of RAP in asphalt mixtures can be significantly increased with the application of good RAP management practice, readily available modern production technologies and advanced knowledge of mix design. This paper summarises the state-of-the-art approaches for increasing the amount of RAP in asphalt mixtures above 40%. The production challenges and common pavement distresses of very high RAP content mixtures are identified and methods to optimise the mix design as well as production technology in order to allow manufacturing of such sustainable mixtures are described. The best practices for RAP management and economic benefits of high RAP use are also discussed.